JPS62282162A - Fuel filter device for diesel engine - Google Patents

Abstract

PURPOSE:To obtain such a constitution as it is advantageous both in installation and in cost by integrally incorporating a gas-liquid separating and reverse-flow preventing device into an injection pump body, so that the heat having been lost from the fuel piping and the equipment itself can be minimized as far as possible. CONSTITUTION:In the interior of a gas-liquid separating and reverse-flow preventing device body consisting of an injection pump housing 15A and a cover 24 arranged and fixed on the upper part thereof, a float chamber 23 which houses a float 25 as a liquid surface responsively moving member is provided. The heated fuel from an injection pump 15 is introduced into the float chamber 23 via an overflow fuel introducing passage 31 and a communicating hole 32 in the gas-liquid separating and reverse-flow preventing device. The gas-liquid separation of overflow fuel due to the difference in specific gravity is carried out in the float chamber 23, and only the fuel accompanied with bubbles pushes a check valve 26 open to be returned to a fuel tank 1. The overflow fuel is introduced into a fuel filter 3 through a discharge port 29.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a fuel filter device provided in a fuel supply system of a diesel engine.

<Prior art> Fuels mainly composed of light oil used as diesel engine fuel tend to precipitate wax at low temperatures, for example, below -10°C, and this tends to adhere to the fuel filter element and cause clogging. . When such a phenomenon occurs, the flow of fuel supplied to the engine is cut off, resulting in inconveniences such as insufficient engine output, stopping, and stalling or stopping of the vehicle.

In an attempt to solve this inconvenience, Japanese Patent Application Laid-Open No. 1986-
There are disclosures such as No. 164657.

An example of this is shown in FIGS. 4 and 5.

In FIG. 4, fuel in a fuel tank 1 is passed through a supply passage 2, filtered by a fuel filter 3, and then sucked into an injection pump 4 such as a distribution type fuel injection pump. The injection pump 4 is equipped with a feed pump and a pressure regulator, and the fuel sucked by the feed pump is maintained at an appropriate pressure by the pressure regulator to lubricate and cool each moving part and is guided to the pump part.

The fuel sucked into the pump section is distributed under pressure and guided to an injection nozzle 5 disposed in each cylinder of the diesel engine, from which it is injected and supplied.

Here, in order to cool itself, the injection pump 4 feeds extra fuel in excess of the amount of fuel required for injection, and the injection pump 4 uses this extra fuel and the surplus fuel that was sent to the injection nozzle 5 but not used for injection. is returned to the fuel tank 1 via return passages 6, 7.8.

This so-called overflow fuel is heated by the mechanical work of the injection pump 4, so it is heated by several degrees (approximately 6 degrees
°C), and the heat is normally dissipated in the fuel tank 1.

As shown in FIG. 5, the gas-liquid separation and backflow prevention device 9 installed in the return passage 8 is equipped with a float chamber 11 having a built-in float 10, so that overflow fuel containing bubbles flows into the float chamber. 11, where gas-liquid separation is performed based on the difference in specific gravity, and only the fuel with bubbles in the upper part is released into the fuel tank 1 by pushing open the check valve 12. In the float chamber IX, when the stored amount of overflow fuel falls below a predetermined value, the float 10 descends along with the liquid level and closes the discharge port 13 provided in the bottom wall. As a result, only overflow fuel without air contamination is led out from the discharge port 13.

The discharge port 13 is connected to the inlet port 3a of the fuel filter 3 via a heating fuel passage 14, and overflow fuel is guided to the fuel filter 3 to heat the fuel.

<Problems to be Solved by the Invention> However, in such a conventional diesel engine fuel filter device, as described above, the gas-liquid separation and backflow prevention device 9 is configured completely independently of other devices. For example, since it is separated from the injection pump 4 main body and the fuel filter 3 main body, the following problems occur.

That is, it is often subject to restrictions on the installation location when mounted on a vehicle. As a result, the fuel hose 7A constitutes a portion that connects the gas-liquid separation and backflow prevention device 9 and the injection pump 4 and a portion that connects the gas-liquid separation and backflow prevention device 9 and the fuel filter 3.

14A had to be made longer, and the fuel hoses 7A and 14A
The heat of the fuel is dissipated and lost while the fuel passes through the
The fuel filter element becomes increasingly clogged. Heat is also dissipated from the main body of the gas-liquid separation and backflow prevention device 9 itself. Furthermore, since there are more items that can be damaged due to vehicle accidents, etc., the frequency of damage to the fuel system is high, and safety considerations have to be taken with regard to fuel piping. Furthermore, since the number of overall components increases, it is also disadvantageous in terms of cost.

As described above, the conventional devices have problems in terms of characteristics and installation, and are also disadvantageous in terms of cost.

The present invention has been made in view of these conventional problems, and solves the problem that the gas-liquid separation and backflow prevention device is configured independently from other devices, thereby improving characteristics, installation, and cost. The purpose is to create an advantageous configuration.

Means for Solving the Problems> For this reason, the present invention provides a fuel filter installed in a supply passage that supplies fuel to an injection pump, and a part of the fuel that is heated by the injection pump and overflows from the fuel filter. In a diesel engine fuel filter device comprising a heated fuel passage leading to the upstream side of the fuel filter and a temperature-sensitive valve device interposed in the heated fuel passage, the gas-liquid separation and backflow prevention device is connected to the injection It is integrated into the pump body.

(Function) With this configuration, wasteful heat dissipation while the fuel travels from the injection pump to the gas-liquid separation and backflow prevention device is eliminated.
The heat dissipated from the gas-liquid separator and backflow prevention device is efficiently absorbed by the injection pump body, which suppresses heat dissipation while the fuel travels from the gas-liquid separation and backflow prevention device to the fuel filter, increasing the efficiency of fuel heating. Also, it is possible to eliminate the fuel hose, etc. that forms the part of the heating fuel passage that connects the gas-liquid separation/backflow prevention device and the injection pump, reducing the number of overall components and reducing damage to the fuel system. This means that the frequency can be reduced.

<Example> Hereinafter, an example of the present invention will be described based on FIGS. 1 to 3.

In FIG. 1, a fuel filter 3 interposed in a supply passage 2 that supplies fuel to an injection pump 15, and
As is the case with the prior art, it includes a heating fuel passage 14 that guides a portion of the fuel that is heated and overflows to the upstream side of the fuel filter 3.

The structure of the fuel filter 3 will be explained based on FIG. The connected upper cover 20 has a supply port 21 connected to the supply passage 2A on the fuel tank 1 side and a discharge port 22 connected to the supply passage 2B on the injection pump 4 side. 19, and the discharge port 22 is connected to the downstream side of the filter element 18.
A heating fuel supply port 30 is opened which communicates with the center vibe 19 together with the supply port 21, and at the opening on the center vibe 19 side there is a W'/ An L valve device 33 is installed.

In this fuel filter 3, 39 is an overflow passage that bypasses the supply port 21 and the discharge port 22 without passing through the filter element 18, and check valves 40 and 41 are interposed in the overflow passage 39. There is. Therefore, if clogging occurs, the supply port 2
The fuel pressure on the 1 side increases and opens the check valves 40, 41, directing the fuel flow to the injection pump 15 without filtration to prevent the engine from stalling.

42 is a manual pump for venting air from the fuel line, 43
44 is a water level sensor for notifying the water level accumulated in the water separator 43 and issuing a warning; 45 is a drain cock.

The gas-liquid separation and backflow prevention device 16 interposed on the upstream side of the temperature-sensitive valve device 33 in the heated fuel passage 14 is integrated into the main body of the injection pump 15.

That is, inside the main body of the gas-liquid separation and backflow prevention device 16, which is composed of an injection pump housing 15A and a cover 24 arranged and fixed on the upper part thereof, there is a space formed by storing a float 25 as a liquid level responsive member. A float chamber 23 is provided. The cover 24 is provided with a discharge port 27 that communicates with the fuel tank 1 via a check valve 26 as a backflow prevention means. In addition, an overflow fuel introduction passage 31 is formed in the main body of the gas-liquid separation and backflow prevention device 16, extending from the bottom of the main body to the top, and equipped with an O-HARZ 35 inside. The introduction passage 31 communicates with the inside of the float chamber 23 via a communication hole 32. A discharge port 29 having a float valve seat portion 29a is provided in the bottom wall of the float chamber 23, and the discharge port 29 communicates with the fuel filter 15 via the heated fuel passage 14 and the temperature-sensitive valve device 33. It communicates with the fuel passage 34.

Next, the operation of this configuration will be explained.

The fuel sucked up from the fuel tank 1 is passed through the fuel filter 3
is filtered by the filter element 18 of the supply passage 2.
The wax component in the fuel precipitates when the fuel temperature drops below a certain temperature.
Clogging occurs in the filter element 18.

In such a case, the temperature-sensitive valve device 33 using a bimetal detects this fuel temperature and opens the valve, and the injection pump 15 is opened.
The heated fuel is introduced into the float chamber 23 through the overflow fuel introduction passage 31 and communication hole 32 of the gas-liquid separation and backflow prevention device 16.

The overflow fuel undergoes gas-liquid separation based on the difference in specific gravity in the float chamber 23, and only the fuel with bubbles in the upper part is returned to the fuel tank 1 by pushing open the check valve 26. The overflow fuel from which bubbles have been separated in the float chamber 23 passes through the discharge port 29, with heat loss suppressed to the minimum possible.
The fuel passes through the open check valve of the temperature-sensitive valve device 33 from the fuel passage 34 and is introduced into the center pipe 19 .

Therefore, the fuel circulates through the injection pump 15 - fuel filter 3 - injection pump 15 circulation circuit, and the fuel temperature rises until the extreme temperature halving device 33 closes, preventing the wax component from precipitating. , it is possible to prevent the filter element from clogging for one day. Also, with the rise in fuel temperature! ! ! The introduction of overflow fuel for heating is gradually reduced because the opening area of the check valve becomes smaller in accordance with thermal deformation of the bimetal of the temperature-sensitive valve device 33. Furthermore, when the fuel temperature reaches a high temperature higher than the set value, the temperature-sensitive valve device 33 closes to cut off the introduction of overflow fuel.

In the manner described above, proper fuel heating is performed.

According to this configuration, since the gas-liquid separation and backflow prevention device 16 is integrated into the injection pump 15 main body, wasteful heat dissipation while the fuel reaches the gas-liquid separation and backflow prevention device 16 from the injection pump I5 is avoided. The heat dissipated from the gas-liquid separator and backflow prevention device 16 is efficiently absorbed into the injection pump 15 body, so that the heat dissipated while the fuel reaches the fuel filter 3 from the gas-liquid separation and backflow prevention device 16 is also efficiently absorbed. and doubles the efficiency of fuel heating. By reducing the number of independently configured devices by one, it is no longer necessary to be subject to restrictions on the installation location when mounted on a vehicle, improving ease of mounting on a vehicle, and further reducing the risk of vehicle accidents. Since the number of items that can be damaged can be reduced, the frequency of fuel system damage can be reduced and safety can be improved. Furthermore, since the number of overall components is reduced, it is advantageous in terms of cost.

In addition, in this configuration, since the gas-liquid separation/backflow prevention device 16 is integrated into the injection pump 15 body, when the overflow fuel is used under high temperature conditions, it receives new heat while reaching the fuel tank 1. This prevents the fuel from heating up excessively.

Incidentally, when the fuel is used under high temperature conditions, if the fuel is heated excessively, the specific gravity and viscosity of the fuel will decrease, causing the injection pump 1
There is concern that the injection amount from No. 5 will decrease, leading to a decrease in output.

<Effects of the Invention> As explained above, according to the present invention, the gas-liquid separation and backflow prevention device, which has conventionally been configured independently of other devices, for example, is provided separately from the injection pump body, can be improved. By integrating it into the injection pump body, the heat lost from the fuel piping and the device itself can be minimized, improving vehicle mountability, reducing danger in the event of an accident, and reducing costs by reducing overall component parts. Many effects can be obtained. or,
With a configuration in which the gas-liquid separation and backflow prevention device is integrated into the injection pump body, when used under high-temperature conditions, overflow fuel does not receive additional heat while reaching the fuel tank, and the fuel is not heated excessively. Therefore, there is no possibility that the specific gravity and viscosity of the fuel will decrease, the injection amount will decrease, or the output will decrease due to excessive heating of the fuel.

[Brief explanation of the drawing]

Fig. 1 is a system diagram showing one embodiment of the filter device according to the present invention, Fig. 2 is a cross-sectional view of the gas-liquid separation and backflow prevention device portion in the same device, and Fig. 3 is a front cross-section of the fuel filter in the same device. 4 is a system diagram of a conventional filter device, and FIG. 5 is a sectional view of a gas-liquid separation and backflow prevention device in the same filter device. 1... Fuel tank 2... Supply passage 3...
Fuel filter 14...Heating fuel passage 15...
・Injection pump 16... Gas-liquid separation and backflow prevention device
23...Vacancy (float chamber) 25...Liquid level response member (flow 1-) 26...Backflow prevention means (check valve) 27...Discharge port 29...Discharge port 31
...Overflow fuel introduction passage 32...Communication hole 33...Temperature-sensitive valve device 34...Fuel passage Patent applicant Nissan Motor Co., Ltd. Representative Patent attorney Fujio Sasashima Figure 1@2 Figure 3

Claims (1)

[Claims] a fuel filter interposed in a supply passage that supplies fuel to an injection pump; a heating fuel passage that guides a portion of fuel heated by the injection pump and overflowing from the supply passage to the upstream side of the fuel filter; and the heating fuel passage. A fuel filter device for a diesel engine, comprising: a temperature-sensitive valve device installed in the heated fuel passage; , has a cavity in which a liquid level responsive member is disposed, a discharge port communicating with the upstream side of the temperature-sensitive valve device and opened and closed by the liquid level responsive member at the bottom, and an overflow fuel outlet at the top. A fuel for a diesel engine, characterized in that a gas-liquid separation and backflow prevention device comprising an inlet port and a discharge port communicating with a fuel tank through a backflow prevention means is integrated into the injection pump body. filter device.